We have successfully fabricated barium titanate (BaTiO3) films on Si (100) and Pt(111)/Ti/SiO2/Si substrates using the polyol thermal decomposition (PTD) process by spin-coating technique. In PTD process, we confirmed that the crystalline oxycarbonate Ba2Ti2O5CO3 films were directly formed as a consequence of evaporation of polyol precursor solution prepared simply by mixing metal chlorides and ethylene glycol, and then converting them into crystalline BaTiO3 films through thermal decomposition at > 500 A degrees C. This feature makes it possible to grow densely packed and crack-free BaTiO3 films as thin as 70 per cycle. Although PTD is described here for a complex metal-oxide film of BaTiO3, other simple and complex metal-oxide thin films with high-dielectric constant materials are also likely to be suitable for deposition with accurate control of film thickness and composition using the polyol precursor solutions.